Light-emitting device and method of manufacturing the light-emitting device

ABSTRACT

A light-emitting device includes: a package defining a recess; a light-emitting element disposed on a bottom surface of the recess; and a sealing member disposed in the recess so as to cover the light-emitting element. The sealing member includes a filler-containing layer which contains a filler and covers the light-emitting element, and a light-transmissive layer disposed on the filler-containing layer. The recess is further defined by a lateral surface having a stepped portion between the bottom surface of the recess and an opening of the recess. The light-transmissive layer covers the stepped portion. An upper surface of the light-transmissive layer is downwardly recessed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/995,016, filed on Aug. 17, 2020, which claims priority to JapanesePatent Application No. 2019-149936, filed on Aug. 19, 2019, the contentsof which are hereby incorporated by reference in their entirety.

BACKGROUND

The present disclosure relates to a light-emitting device and a methodof manufacturing the light-emitting device.

Light-emitting devices have been used for headlights or the like ofvehicles. Light-emitting devices for the exteriors of vehicles arerequired to emit high-luminance light (see, for example, Japanese PatentPublication No. 2017-108091).

SUMMARY

Light-emitting devices for the interiors of vehicles may be required tohave a low luminous intensity when the light-emitting devices are turnedon.

An object of certain embodiments of the present disclosure is to providea light-emitting device that has a low luminous intensity when thelight-emitting device is turned on, and a method of manufacturing thelight-emitting device.

According to one embodiment of the present disclosure, a light-emittingdevice includes: a package defining a recess; a light-emitting elementmounted on a bottom surface of the recess; and a sealing member disposedin the recess to cover the light-emitting element and made of alight-transmissive resin that contains a filler with an average particlediameter of 200 nm or more and 500 nm or less. The sealing memberincludes a filler-containing layer, which contains the filler, and alight-transmissive layer that are layered in an order from the bottomsurface side of the recess. The filler-containing layer has a thicknessof equal to or larger than a height of the light-emitting element.

According to another embodiment of the present disclosure, a method ofmanufacturing a light-emitting device includes: providing at least onepackage each defining a recess; mounting a light-emitting element on abottom surface of the recess; supplying an uncured sealing member intothe recess, the uncured sealing member containing a light-transmissiveresin and a filler in the light-transmissive resin, the filler having anaverage particle diameter of 200 nm or more and 500 nm or less; andapplying a centrifugal force to the package in a direction perpendicularto the bottom surface of the recess to sediment the filler toward thebottom surface of the recess to form a filler-containing layer, whichcontains the filler, and a light-transmissive layer in an order from thebottom surface side of the recess.

Certain embodiments of the present disclosure allow for providing alight-emitting device that has a low luminous intensity when thelight-emitting device is turned on, and a method of manufacturing thelight-emitting device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating an entirety of alight-emitting device according to one embodiment.

FIG. 2 is a schematic plan view of the light-emitting device accordingto one embodiment.

FIG. 3 is a schematic cross-sectional view taken along line of FIG. 2 .

FIG. 4 is a flowchart illustrating a method of manufacturing thelight-emitting device according to one embodiment.

FIG. 5 is a schematic partial enlarged view of a lead frame,illustrating a resin body disposed on a first lead and a second lead inthe method of manufacturing the light-emitting device according to oneembodiment.

FIG. 6 is a schematic partial enlarged view of the lead frame,illustrating a light-emitting element and a protective element that aredisposed in a recess of the resin body in the method of manufacturingthe light-emitting device according to one embodiment.

FIG. 7 is a schematic enlarged view of the lead frame with thelight-emitting device disposed thereon, illustrating the recess filledwith a sealing member in the method of manufacturing the light-emittingdevice according to one embodiment.

FIG. 8 is a schematic diagram illustrating a step of sedimenting using acentrifugal force in the method of manufacturing the light-emittingdevice according to one embodiment.

FIG. 9 is a schematic enlarged plan view illustrating a singulatedlight-emitting device in the method of manufacturing the light-emittingdevice according to one embodiment.

FIG. 10 is a schematic cross-sectional view taken along line X-X of FIG.9 .

DETAILED DESCRIPTION

A light-emitting device and a method of manufacturing the light-emittingdevice according to certain embodiments will be described. The drawingsreferred to in the descriptions below schematically illustrate certainembodiments of the present invention. The scales, the distances, thepositional relationships, and the like of members may be exaggerated, orillustration of portions of members may be omitted. In the descriptionsbelow, the same term or reference numeral generally represents the samemember or a member made of the same material, and its detaileddescription will be omitted when appropriate.

Structure of Light-Emitting Device

Descriptions will be made with reference to the drawings. FIG. 1 is aschematic perspective view illustrating an entirety of a light-emittingdevice according to one embodiment. FIG. 2 is a schematic plan view ofthe light-emitting device according to one embodiment. FIG. 3 is aschematic cross-sectional view taken along a line of FIG. 2 .

The light-emitting device 1 includes a package 100 defining a recess 11,a light-emitting element 31 disposed on a bottom surface 15 of therecess 11, and a sealing member 50 disposed in the recess 11 to coverthe light-emitting element 31. The sealing member is made of alight-transmissive resin 51 that contains a filler 52 with the averageparticle diameter of 200 nm or more and 500 nm or less. In thelight-emitting device 1, the sealing member 50 includes afiller-containing layer L2 that contains the filler 52, and alight-transmissive layer L1 in this order from the bottom surface 15side of the recess 11. The filler-containing layer L2 has a thicknesslarger than a height of the light-emitting element 31. That is, anentirety of the light-emitting element 31 is covered with thefiller-containing layer L2.

Configurations of the light-emitting device 1 will be described below.

Package

The package 100 includes a first lead 41, a second lead 42, and a resinbody 10 that integrally holds the first lead 41 and the second lead 42.The package 100 defines the recess 11. The recess 11 is defined by thebottom surface 15 and lateral surfaces 13 that surround the bottomsurface 15. The recess 11 has an opening at upper portions of thelateral surfaces 13, and widens upward from the bottom surface 15 towardthe opening of the recess 11. Further, the recess 11 has a steppedportion 12 between the bottom surface 15 and the opening. The steppedportion 12 in this example is located near the opening at the upperportions of the lateral surfaces 13 such that the opening has an areathat increases upward from the bottom surface 15 of the recess 11.

The outer periphery of the resin body 10 has a substantially rectangularshape in a plan view. The resin body 10 includes a wall portion thatdefines the lateral surfaces 13 of the recess 11, and a holding portion14 that integrally holds the first lead 41 and the second lead 42 at thelower portion of the wall portion.

The holding portion 14 includes a central bottom portion 14 a that islocated between the first lead 41 and the second lead 42, and aperipheral portion 14 b that has a frame shape surrounding the firstlead 41 and the second lead 42 in a plan view. The central bottomportion 14 a is formed to secure a distance between the first lead 41and the second lead 42 for electrical insulation.

The bottom surface of the recess 11 is defined by a portion of the firstlead 41, a portion of the second lead 42, and the central bottom portion14 a.

Further, the resin body 10 has the stepped portion 12 on a peripheralportion of the lateral surfaces 13 near the opening of the recess 11 soas to increase the opening area from the bottom surface 15 to theopening. The stepped portion 12 serves as, for example, an indication ofthe boundary between the light-transmissive layer L1 and thefiller-containing layer L2, which will be described below. With thestepped portion 12, the opening area of the resin body 10 increases,resulting in increase of the light irradiation surface. This allows forreducing the light intensity per unit area of the light-emitting device1. Also, in the light-emitting device 1, adhesion of the resin body 10to the sealing member 50 can be increased.

Examples of the resin body 10 include thermoplastic resins andthermosetting resins.

Examples of thermoplastic resins to be used include polyphthalamideresins, liquid crystal polymers, polybutylene terephthalate (PBT), andunsaturated polyesters.

Examples of thermosetting resins to be used include epoxy resins,modified epoxy resins, silicone resins, and modified silicone resins.

The resin body 10 may contain a light-reflective member. For example,titanium oxide, zinc oxide, zirconium oxide, aluminum oxide, siliconoxide, glass filler, silica, magnesium oxide, antimony oxide, aluminumhydroxide, barium sulfate, magnesium carbonate, and barium carbonate,which are relatively stable against moisture and have a high refractiveindex and high thermal conductivity, are preferably used for thelight-reflective member.

Each of the first lead 41 and the second lead 42 includes an inner leadportion forming the bottom surface 15 of the recess 11 in the package100, and an outer lead portion located at the outer side of the resinbody 10 and at a lower surface of the package 100. At the bottom surface15 of the recess 11, each of the first lead 41 and the second lead 42has an area that is large enough to dispose a semiconductor element 30,namely the light-emitting element 31 or a protective element 32, on thebottom surface 15 and establish electrical connection to thesemiconductor element 30 via wires 33 and 34. The outer lead portion ofeach of the first lead 41 and the second lead 42 is exposed at the lowersurface of the resin body 10 and protrudes laterally from the peripheralportion 14 b of the resin body 10. The lower surface of the package 100serves as a mounting surface to be mounted on a secondary mountingsubstrate. A portion of the lower surface of each of the first lead 41and the second lead 42 is a portion of the outer lead to serve as anexternal electrode for the light-emitting device 1. In a plan view ofthe package 100, a central portion of the outer lead defines adepression.

Examples of materials preferably used for the first lead 41 and thesecond lead 42 include copper and a copper alloy. The outermost surfacesof each of the first lead 41 and the second lead 42 may be plated with,for example, silver, aluminum, copper, or gold.

Ceramic packages that include wiring portions may be used for thepackage defining a recess.

The light-emitting element 31 is mounted on the bottom surface 15 of therecess 11 of the package 100. In one example, the light-emitting element31 is mounted on the first lead 41 and electrically connected to thefirst lead 41 and the second lead 42 via the wires 33. The emissioncolor of the light-emitting element 31 can be selected from anyappropriate wavelength according to the purpose. Examples oflight-emitting elements configured to emit blue light (light with awavelength in a range of 430 nm to 490 nm) to be used include nitridesemiconductors of GaN-based or InGaN-based semiconductors that can berepresented by In_(x)Al_(y)Ga_(1-x-y)N (where 0≤X≤1, 0≤Y≤1, and X+Y≤1).The light-emitting element 31 can be mounted in a face-up manner inwhich a surface provided with electrodes faces upward or in a flip-chipin which a surface provided with electrodes faces downward. Theprotective element 32 may be mounted on the first lead or the secondlead.

The protective element 32 is, for example, a Zener diode that protectsthe light-emitting element 31 against electric breakdown. In an example,the protective element 32 is mounted on the second lead 42 andelectrically connected to the first lead 41 via the wire 34. While theconfiguration in which the light-emitting element 31 and the protectiveelement 32 are disposed as the semiconductor elements 30 is describedabove, the protective element 32 may be omitted, or a plurality oflight-emitting elements 31 may be disposed.

The wires 33 and 34 are electroconductive wirings, each electricallyconnecting a corresponding one of the semiconductor elements 30, such asthe light-emitting element 31 and the protective element 32, with acorresponding one of the first lead 41 and the second lead 42. Examplesof a material of the wires 33 and 34 include metals such as Au (gold),Ag (silver), Cu (copper), Pt (platinum), Al (aluminum), and alloys ofthese metals. Among these, Au is preferable in view of reliability.

The sealing member 50 is disposed in the recess 11 and covers thelight-emitting element 31 and other components. The sealing member 50 isdisposed to protect the light-emitting element 31 and the like againste.g., external forces, dust, and moisture, and to improve heatresistance, weather resistance, and light resistance of thelight-emitting element 31 and the like. The sealing member 50 includesthe filler-containing layer L2 containing the filler 52 and thelight-transmissive layer L1 in this order from the bottom surface 15 ofthe recess 11. In one example, the sealing member 50 contains a phosphor53 as well as the filler 52, and a phosphor layer L3 is formed along thebottom surface 15.

The sealing member 50 is light-transmissive for light emitted from thelight-emitting element 31. More specifically, the sealing member 50contains, as a base material, a light-transmissive resin 51 such as asilicone resin, an epoxy resin, or a urea resin. Further, the sealingmember 50 includes the filler 52 serving as a material to reduce anamount of light emitted from the light-emitting element 31. The sealingmember 50 may include materials as an additive member other than thefiller 52. In the present embodiment, the sealing member 50 includes thephosphor 53.

In the case in which the sealing member 50 includes the phosphor 53, thephosphor layer L3 that includes the phosphor 53 is preferably disposedbetween the bottom surface of the recess 11 and the filler-containinglayer L2. That is, the sealing member 50 includes the phosphor layer L3,the filler-containing layer L2, and the light-transmissive layer L1 inthis order from the bottom surface 15 side of the recess 11. Theboundaries between adjacent ones of the light-transmissive layer L1, thefiller-containing layer L2, and the phosphor layer L3 are not clearlyformed but are varied gradually in a predetermined range of each layerboundary. In the sealing member 50, the light-transmissive layer L1, thefiller-containing layer L2, and the phosphor layer L3 are formed usingcentrifugal sedimentation in which a centrifugal force is applied forsedimentation, which will be described below.

The light-transmissive layer L1 is a supernatant layer obtained bysedimenting the filler and the phosphor in the sealing member 50 usingthe centrifugal force. The light-transmissive layer L1 is made of thelight-transmissive resin 51 and has an upper surface that serves as alight extraction surface of the light-emitting device 1. The uppersurface of the light-transmissive layer L1 (that is, the upper surfaceof the sealing member 50) may be a flat surface parallel to the bottomsurface 15, or may be a concave surface having a central portion locatedlowest gradually curved toward the periphery of the opening. In a regionbetween the bottom surface 15 of the recess 11 and the upper surface ofthe sealing member 50, the light-transmissive layer L1 may have athickness of 30% or less, 20% or less, or 10% less of a distance betweenthe upper surface of the sealing member 50 and the bottom surface 15.

The filler-containing layer L2 has a thickness equal to or larger than aheight of the light-emitting element 31. The filler-containing layer L2has a substantially flat upper surface located above the upper surfaceof the light-emitting element 31. In one example, the filler-containinglayer L2 preferably has a height that is greater than the height of thetop portion of the wire 33, connected to the light-emitting element 31,from the bottom surface 15, and more preferably has a height that istwice or more the height of the light-emitting element 31. The uppersurface of the filler-containing layer L2 above the bottom surface 15 islocated below the stepped portion 12. Accordingly, the filler-containinglayer L2 does not cover the stepped portion 12, while the steppedportion 12 is covered by the light-transmissive layer L1 that containssubstantially no filler. This structure allows for further improvingadhesion between the package and the sealing member 50. Thefiller-containing layer L2 may be disposed in a region between thebottom surface 15 and the opening of the recess 11 to have a height in arange of 70% to 90% of the height from the bottom surface 15 toward theopening.

A filler having an average particle diameter of 200 nm or more and 500nm or less is preferably used for the filler 52. With a particlediameter of 200 nm or more, the fillers 52 can easily scatter light invisible light region. However, with the particle diameter exceeding 500nm, light transmissivity in the filler-containing layer L2 may bereduced, so that the scattered light may not be easily extracted to theoutside. With the filler 52 having the average particle diameter withinthe range described above, light emitted from the light-emitting element31 can be efficiently scattered when the light passes through thefiller-containing layer L2 and the scattered light can be efficientlyextracted to outside. Accordingly, a light-emitting device with reducedglare and a reduced luminous intensity can be obtained.

The filler 52 preferably has a spherical shape or a shape close to aspherical shape for ease of fluidity in the light-transmissive resin 51.This allows the filler 52 to be accumulated in the filler-containinglayer L2 at a substantially uniform concentration.

The content of the filler 52 is preferably in a range of 2 to 10 mass %in the light-transmissive resin. If the content of the filler 52 islower than 2 mass %, the light intensity may be greater than a requiredlow intensity. If the content of the filler 52 is greater than 10 mass%, light may be reflected among the fillers 52, so that light is noteasily extracted, which may result in excessively small the lightintensity.

Examples of a technique for measuring the average particle diameterinclude laser diffraction and scattering, image analysis (such asscanning electron microscopy (SEM) and transmission electron microscopy(TEM)), dynamic light scattering, and small-angle X-ray scattering.

Examples of the filler 52 include titanium oxide, silica, silicon oxide,aluminum oxide, zirconium oxide, magnesium oxide, potassium titanate,zinc oxide, and boron nitride. Among these materials, titanium oxide,which has a comparatively high refractive index, is preferably used inview of reflection of light.

Known surface treatments using agents such as silane coupling agent ortitanium-coupling agent may be applied to the filler 52. For the agentsused for the surface treatment, silane coupling agents is preferableused, and aminosilane is particularly preferably used. Performingsurface treatment using the silane coupling agent and the like allowsfor facilitating mixing of the filler 52 and the light-transmissiveresin 51 and smoothening the surface of the filler 52. This isconsidered to facilitate sedimentation of the filler 52.

In the sealing member 50, the phosphor 53 forms the phosphor layer L3and is disposed on the upper surface of the light-emitting element 31and the bottom surface 15 of the recess 11. The phosphor layer L3 isformed to have a thickness equal to or less than a half of the height ofthe light-emitting element 31.

A phosphor having a higher specific gravity than the filler 52 ispreferably used for the phosphor 53. This allows the phosphor 53 to besedimented at a portion closer to the bottom surface 15 of the recess11. The average particle diameter of the phosphor 53 is, for example, 3μm or more and 50 μm or less.

A substance known in the art can be used for the phosphor 53. Forexample, a yellow phosphor such as YAG (Y₃Al₅O₁₂:Ce) or silicates, a redphosphor such as CASN (CaAlSiN₃:Eu) or KSF (K₂SiF₆:Mn), or a greenphosphor such as chlorosilicates or BaSiO₄:Eu²⁺ can be used. A pluralityof types of phosphors may be used in combination. For example, phosphorshaving different luminescent colors may be used in combination or in ablending ratio appropriate for a desired color to adjust color renderingproperties or color reproducibility.

Method of Manufacturing Light Emitting Device

Next, a method of manufacturing the light-emitting device 1 will bedescribed with reference to FIGS. 4 to 10 . FIG. 4 is a flowchartillustrating the method of manufacturing the light-emitting deviceaccording to one embodiment. FIG. 5 is a schematic partial enlarged viewof a lead frame, illustrating a resin body disposed on a first lead anda second lead in the method of manufacturing the light-emitting deviceaccording to one embodiment. FIG. 6 is a schematic partial enlarged viewof the lead frame, illustrating a light-emitting element and aprotective element that are disposed in a recess of the resin body inthe method of manufacturing the light-emitting device according to oneembodiment. FIG. 7 is a schematic enlarged diagram of the lead frame onwhich the light-emitting device is disposed, illustrating the recessbeing filled with a sealing member in the method of manufacturing thelight-emitting device according to the embodiment. FIG. 8 is a schematicdiagram illustrating a step of sedimenting using a centrifugal force inthe method of manufacturing the light-emitting device according to theembodiment. FIG. 9 is a schematic enlarged plan view illustrating asingulated light-emitting device in the method of manufacturing thelight-emitting device according to the embodiment. FIG. 10 is aschematic cross-sectional view taken along line X-X of FIG. 9 .

The method of manufacturing the light-emitting device includes: a stepS11 of providing a package 100 defining a recess 11; a step S12 ofmounting a light-emitting element 31 on a bottom surface 15 of therecess 11; a step S13 of supplying an uncured sealing member 50 thatincludes a light-transmissive resin 51 containing a filler 52 with anaverage particle diameter of 200 nm or more and 500 nm or less into therecess 11; and a step S14 of sedimenting the filler 52 toward the bottomsurface 15 using a centrifugal force applied to the package 100 in adirection perpendicular to the bottom surface 15 of the recess 11 toform a filler-containing layer L2 that contains the filler 52 and alight-transmissive layer L1 in this order from the bottom surface 15 ofthe recess 11. In the method of manufacturing the light-emitting device,the sealing member 50 may further include a phosphor 53 and in the stepS14 of sedimenting using a centrifugal force, a phosphor layer L3 thatincludes the phosphor 53 may be disposed at a portion closer to thebottom surface 15 of the recess 11 than the filler-containing layer L2.

Step S11 of Providing a Package

In the step S11 of providing a package, the package 100 defining therecess 11 is provided. In one example, a lead frame LF formed with aplurality of resin bodies 10 is provided to provide packages 10 eachincluding a corresponding portion of the lead frame LF and acorresponding one of the resin bodies 10. In each drawing, a singlepackage 100 is shown, and illustration of other packages 100 is omittedto simplify the description. The lead frame LF used herein is made of,for example, good electric conductors such as copper or copper alloys,and can have a flat metal plate shape. Alternatively, a metal plate witha stepped portion or an uneven surface may also be used. The lead frameLF is formed by punching or etching a flat metal plate. A portion of thelead frame LF corresponding to a single package 100 includes a firstlead 41 and a second lead 42.

Other examples of a structure having packages each defining a recessinclude a collective substrate including ceramic packages provided withwiring members.

Step S12 of Mounting a Light Emitting Element

In the step S12 of mounting a light emitting element, the light-emittingelement 31 is mounted on the bottom surface 15 of the recess 11 of thepackage 100. Instead of the light-emitting element 31, the semiconductorelement 30 such as a protective element 32 may be mounted. Thelight-emitting element 31 used in this example includes a pair ofelectrodes on the same surface side (for example, the upper surfaceside). In this case, the light-emitting element 31 is mounted via anadhesive applied on the first lead exposed at the bottom surface 15 ofthe recess 11 of the package 100, and the electrodes of thelight-emitting element 31 are electrically connected to the first leadand the second lead via respective wires 33. Also, when using anupper-and-lower electrode type light emitting element, either one of theupper and lower electrodes is mounted on a corresponding one of theleads via an electroconductive adhesive, while the other one of theupper and lower electrodes is electrically connected to anothercorresponding one of the leads via a wire 33. Also, when using anupper-and-lower electrode light-emitting element, the electricalconnection to the first lead is established using electroconductiveadhesive. In this example, an upper-and-lower electrode element is usedfor the protective element 32, and is bonded to the second lead usingthe electroconductive adhesive.

Step S13 of Supplying

In the step S13 of supplying, the uncured sealing member 50 is suppliedinto the recess 11. The sealing member 50 includes thelight-transmissive resin 51 serving as a base material and the filler 52having an average particle diameter of 200 nm or more and 500 nm orless. In the step S13 of supplying, the filler 52 and the phosphor 53are contained in the light-transmissive resin 51. In the step S13 ofsupplying, for example, the uncured resin materials that will be curedto be the sealing member 50 after being cured is supplied into therecess 11 of the package 100 using a resin filling device to seal thelight-emitting element 31 and the protective element 32. The package 100in which the resin material is supplied is subjected to the step S14 ofsedimenting using a centrifugal force.

Step S14 of Sedimenting Using Centrifugal Force

In the step S14 of sedimenting using a centrifugal force, a centrifugalforce is applied to the package 100 in a direction perpendicular to thebottom surface 15 of the recess 11 to sediment the filler 52 and thephosphor 53 toward the bottom surface 15, so that the phosphor layer L3that contains the phosphor 53, the filler-containing layer L2 thatcontains the filler 52, and the light-transmissive layer L1 are formedin this order from the bottom surface 15 side of the recess 11. In thestep S14 of sedimenting using a centrifugal force, the package 100 issubjected to centrifugal rotation such that the centrifugal force isapplied to the bottom surface of the recess 11. This allows the phosphor53 having a high specific gravity to move toward the bottom surface 15of the recess 11, and allows the filler 52 to move near the bottomsurface 15 of the recess 11. Then, in the sealing member 50, the filler52 and the phosphor 53 are accumulated at the bottom surface 15 side ofthe recess 11, so that the light-transmissive layer L1 is formed as asupernatant layer at an outermost surface side. The content of thefiller 52 used herein is in a range of 2 to 10 mass % to thelight-transmissive resin 51. The filler-containing layer L2 has a heightthat is greater than, preferably twice or more, the height of the uppersurface of the light-emitting element 31 from the bottom surface 15. Inthis example, the filler-containing layer L2 is formed such that thefiller 52 is accumulated at a portion from the phosphor layer L3 to aportion directly below the stepped portion 12.

In the present embodiment, the sealing member 50 includes the filler 52.In the sealing member 50, the filler 52 is forcedly accumulated using acentrifugal force toward the bottom surface to form thefiller-containing layer L2. This allows for obtaining a light-emittingdevice 1 having a reduced luminous intensity when the light-emittingdevice 1 is turned on. When the filler-containing layer L2 has athickness described above, the fillers 52 can be arranged with anappropriate clearance between each other. Accordingly, excessivehindering of light extraction due to dense arrangement of the fillers 52can be prevented.

By applying a centrifugal force of more than a predetermined value (forexample, 100×g or more), in the light-transmissive resin 51, thephosphor 53 having a high specific gravity is moved toward the bottomsurface 15, and the filler 52 and the phosphor 53 can be easilyseparated from each other to be the filler-containing layer L2 and thephosphor layer L3, respectively.

The package 100 is preferably rotated about a rotation axis 80 thatallows a centrifugal force to be applied to the package 100 with thebottom surface 15 of the recess 11 facing outward.

More specifically, the package 100 is moved in a direction A thatrevolves around the rotation axis 80 at a positional relationship thatthe upper surface of the package 100 faces the rotational axis 80. Adirection B in FIG. 8 is parallel to the bottom surface of the recess11. The rotation axis 80 is an axis parallel to the bottom surface ofthe recess 11, is located on a line perpendicular to the bottom surfaceof the recess 11 and passing through substantially the center of thebottom surface of the recess 11, and faces the opening of the recess 11of the package 100. Accordingly, a centrifugal force is applied in adirection toward the bottom surface of the recess 11 to reduce spread ofthe sealing member 50 in a height direction of the package 100 and toforcedly sediment the filler 52 and the phosphor 53 contained in thesealing member 50 toward the bottom surface 15 (in the directionindicated by an arrow C in FIG. 8 ) of the recess 11. Curing the sealingmember 50 after forcible sedimentation forms the phosphor layer L3 thatcontains the phosphor 53, the filler-containing layer L2 that containsthe filler 52, and the light-transmissive layer L1 made of thelight-transmissive resin 51 in this order from the bottom surface 15 ofthe recess 11 toward the opening of the recess 11.

The light-transmissive layer L1 and the filler-containing layer L2 areformed to be separated by the stepped portion 12 located at the openingof the recess 11. With the light-transmissive layer L1 covering thestepped portion 12 defining a larger opening area, the irradiation areacan be increased. This can reduce luminance of the light-emitting device1. The boundary of the light-transmissive layer L1 and thefiller-containing layer L2 is not clearly formed, but thelight-transmissive layer L1 and the filler-containing layer L2 areformed such that the number of particles of the filler 52 per unit areais largely reduced at a portion and is gradually reduced from theportion toward the light-transmissive layer L1. The phosphor 53 isdisposed also on the upper surface of the light-emitting element 31 andextends along the bottom surface 15 to form the phosphor layer L3.

The speed and the number of rotation in the centrifugal rotation of thepackage 100 is adjusted according to the content and particle diameterof the filler 52. In one example, the number of rotation and the radiusof gyration is adjusted such that, for example, a centrifugal force of200×g or more and 300×g or less is applied.

When the packages 100 in the state of a collective substrate beforebeing singulated is subjected to centrifugal rotation in themanufacturing, if the collective substrate has a flat plate shape, thelarger the planar area of the collective substrate is, the larger thedeviations of package 100 located away from the center of the collectivesubstrate from the rotation axis 80 are. For example, if the deviationin direction B from the rotation circumference in the collectivesubstrate is large, a surface of the sealing member 50 is inclined tothe bottom surface 15 of the recess 11, and the state of the surface ofthe sealing member 50 may vary over the collective substrate. Thedeviation can be reduced by increasing the radius of gyration. Morespecifically, the deviation can be reduced by employing a radius ofgyration that is 70 times or more as large as the length of thecollective substrate disposed in the direction of rotation.

In the case of using the package 100 having flexibility in which thecollective substrate flexes along the rotation circumference of thegyration radius by the centrifugal force, deviations described above isless likely to occur in the package 100. Thus, rotation can be performedwith a larger collective substrate than in the case of employing acollective substrate including a non-flexible packages 100 under thesame centrifugal force. This can increase the number of packages to betreated at a single time.

Step S15 of Singulating

In the step S15 of singulating, the lead frame LF is divided atpredetermined positions after the sealing member 50 is cured. In thestep S15 of singulating, the lead frame LF is divided into individuallight-emitting devices 1. In a singulated light-emitting device 1, theouter lead portions of the first lead 41 and the second lead 42 protrudelaterally from the lateral surfaces of the package 100 to have apredetermined shape.

Experiment

Light-emitting devices were manufactured in which the phosphor 53 wascontained in the sealing member 50 at the predetermined content, suchthat some of the light-emitting devices contained titanium oxide as thefiller 52 and others of the light-emitting devices did not containtitanium oxide as the filler 52. Luminous intensities were comparedbetween the light-emitting devices that contained titanium oxide as thefiller 52 and the light-emitting devices that did not contain titaniumoxide as the filler 52. The measured data will be described below.

The light-emitting device of a comparative example, which is a referenceof a comparison, contained 6.25 mass % of the YAG phosphor for thephosphor 53 in a silicon resin of the light-transmissive resin 51serving as a base material, without containing titanium oxide as thefiller 52.

In comparison, the light-emitting device according to an embodiment ofthe present disclosure contained 2.7 mass % of titanium oxide having anaverage particle diameter of 250 nm for the filler 52 together with 5.12mass % of the YAG phosphor for the phosphor 53 in the silicone resin ofthe light-transmissive resin 51 serving as a base material.

The packages of the light-emitting devices employed the same structure,which is described below.

The outer shape of the package had a size of 2.2 mm in width, 1.4 mm inlength, and 0.7 mm in thickness. The recess had a size of 1.09 mm by1.62 mm at the opening, with a depth of 0.5 mm. Further, the lead frameLF was made of a copper alloy plated with Ni/Pd/Au. The light-emittingelement had a size of 230 μm in width, 120 μm in length, and 85 μm inthickness. The mounting surface of the light-emitting element wasAl-metalized. The protective element had a size of 180 μm in width andlength and 135 μm in thickness. A thermoplastic resin was used for theresin for the package. The light-emitting element was disposed on theelectrodes of the lead frame LF via a die-bonding material, and asilicone resin was used for the die-bonding material. The wires made ofAu and having a size of 26 μm in diameter were employed.

The light-emitting device of the comparative example and thelight-emitting device according to one embodiment were different in thecontent of the phosphor. Based on the applied currents of 10 mA for thelight-emitting device of the comparative example and 5 mA for thelight-emitting device according to the embodiment, the contents of thephosphor were adjusted such that chromaticity was within an area formedby connecting four points in an XY-chromaticity diagram, namely,(X=0.2730, Y=0.2610), (X=0.2653, Y=0.2709), (X=0.2722, Y=0.2805), and(X=0.2790, Y=0.2700). For values of light-emitting devices in thecomparative example, 89,517 light-emitting devices were examined, andthe average value of the 89,517 light-emitting devices was determined.For values of light-emitting devices in one embodiment, 10,227light-emitting devices were examined, and the average value of the10,227 light-emitting devices was determined.

The average luminous intensity of the light-emitting devices of thecomparative example was 439 mcd with an applied current of 10 mA.Meanwhile, the average luminous intensity of the light-emitting devicesof the embodiment was 75.3 mcd with an applied current of 5 mA. Aspectrometer (OCM-510C) manufactured by Nicety Technologies Inc. wasused as the measuring instrument. It is found that when half a currentof the light-emitting device of the comparative example was applied tothe light-emitting device of one embodiment, the luminous intensity wasapproximately one-fifth of the luminous intensity of the light-emittingdevice of the comparative example. Thus, the result shows thatcontaining the filler 52 with the condition described above in thelight-transmissive resin 51 allowed for reducing the luminous intensity.For reference, luminous intensities of ten light-emitting devices of oneembodiment were measured with the applied current of 10 mA, and theaverage value of the luminous intensities was 152.6 mcd. The photonicmultichannel analyzer (PMA-11) manufactured by Hamamatsu Photonics K.K.was used as the measuring instrument.

While the light-emitting device according to certain embodiments of thepresent disclosure has been specifically described, the scope of thepresent disclosure is not limited by these descriptions and should bebroadly interpreted on the basis of the claims. The scope of the presentdisclosure also encompasses various modifications based on thesedescriptions. For example, in the method of manufacturing thelight-emitting device, while the step of applying a centrifugal force isperformed over a lead frame for a substrate in the description above,the step of applying a centrifugal force may be performed for each ofsingulated light-emitting devices or for groups of a plurality oflight-emitting devices. Also, the stepped portion may have two or moresteps from the upper surface toward the bottom surface of the recess, ormay be in a form of a deep step.

The light-emitting device according to certain embodiments of thepresent disclosure can be used for light-emitting devices for lightingapparatuses and vehicles.

What is claimed is:
 1. A light-emitting device comprising: a packagedefining a recess; a light-emitting element disposed on a bottom surfaceof the recess; and a sealing member disposed in the recess so as tocover the light-emitting element, wherein: the sealing member comprisesa filler-containing layer which contains a filler and covers thelight-emitting element, and a light-transmissive layer disposed on thefiller-containing layer, the recess is further defined by a lateralsurface having a stepped portion between the bottom surface of therecess and an opening of the recess, the light-transmissive layer coversthe stepped portion, and an upper surface of the light-transmissivelayer is downwardly recessed.
 2. The light-emitting device according toclaim 1, wherein: the filler-containing layer has a thickness of twiceor more of the height of the light-emitting element.
 3. Thelight-emitting device according to claim 1, wherein: the sealing memberfurther comprises a phosphor layer containing a phosphor, and thefiller-containing layer is disposed between the phosphor layer and thelight-transmissive layer.
 4. The light-emitting device according toclaim 3, wherein: the phosphor layer covers the bottom surface of therecess and an upper surface of the light-emitting element.
 5. Thelight-emitting device according to claim 3, wherein: the phosphor layerhas a thickness of equal to or less than half the height of thelight-emitting element.